Miniature x-ray unit

ABSTRACT

A miniaturized x-ray apparatus for delivering x-rays to a selected site within a body cavity includes a catheter having at least one lumen and an x-ray transparent window at a distal end thereof; an x-ray source in the lumen adjacent said x-ray transparent window; a movable x-ray shield positioned to direct x-rays from the source through the x-ray transparent window to the selected site.

FIELD OF THE INVENTION

The invention relates to a miniaturized x-ray source situated in acatheter that generates x-rays while minimizing risk from exposure tothe x-rays.

BACKGROUND OF THE INVENTION

Traditionally, x-rays have been used in the medical industry to viewbone, tissue and teeth. X-rays have also been used to treat cancerousand precancerous conditions by exposing a patient to x-rays using anexternal x-ray source. Treatment of cancer with x-rays may cause welldocumented side effects, many of which are due to the broad exposure ofthe patient to the therapeutic x-rays.

To improve medical treatment and diagnosis of patients, minimallyinvasive endoscopic techniques have been developed and are used to treata variety of conditions. Endoluminal procedures are procedures performedwith an endoscope, a tubular device into the lumen of which may beinserted a variety of rigid or flexible tools to treat or diagnose apatient's condition.

The desire for improved minimally invasive medical devices andtechniques have led to the development of miniaturized x-ray devicesthat may be used in the treatment or prevention of a variety of medicalconditions. International Publication No. WO 98/48899 discloses aminiature x-ray unit having an anode and cathode separated by a vacuumgap positioned inside a metal housing. The anode includes a base portionand a projecting portion. The x-ray unit is insulated and connected to acoaxial cable which, in turn, is connected to the power source. An x-raywindow surrounds the projecting portion of the anode and the cathode sothat the x-rays can exit the unit. The x-ray unit is sized forintra-vascular insertion, and may be used, inter alia, in vascularbrachytherapy of coronary arteries, particularly after balloonangioplasty.

International Publication No. WO 97/07740 discloses an x-ray catheterhaving a catheter shaft with an x-ray unit attached to the distal end ofthe catheter shaft. The x-ray unit comprises an anode and a cathodecoupled to an insulator to define a vacuum chamber. The x-ray unit iscoupled to a voltage source via a coaxial cable. The x-ray unit can havea diameter of less than 4 mm and a length of less than about 15 mm, andcan be used in conjunction with coronary angioplasty to preventrestenosis.

Miniaturized x-rays are not foolproof, however, and still presentdifficulties upon use. The x-ray unit generates heat, which can damageadjacent healthy tissue. Additionally, the x-rays are not localized andirradiate local tissue rather than only irradiating the desired tissue.It is difficult to maintain the positioning of these instruments at thedesired location. Improvedminiaturizedx-ray units that overcome thesedifficulties are desirable.

Other techniques are used to treat tumors with radiation, includingplanting a seed of radioactive material at the tumor site, a procedurethat is typically accomplished with endoluminal procedures. However, thepatient becomes “hot”, i.e., radioactive, and the procedure risksexposure of the medical personnel to radiation.

As noted above, many types of cancerous and precancerous conditions aretreated by externally irradiating the tumor or site with x-rays.However, the x-rays are broadcast over a large area of healthy tissue inaddition to the tumor because the radiation is administered from outsidethe body so that it penetrates the skin and any internal organs ortissue to reach the desired site. To avoid this, miniaturized x-raysystems which generate x-rays at the desired site are a desirablealternative to conventional apparatus.

Since many types of cancer occur in a body cavity or lumen, such as inthe rectum, vagina, esophagus or pulmonary passages, it would bedesirable to treat these cancers using miniaturized x-ray sources incombination with endoscopic techniques, which are minimally invasive tothe patient, so that the cancer or other intraluminal tissue is directlytreated with x-rays. This technique would minimize exposure of healthytissues to the x-rays.

The present invention overcomes the difficulties associated with x-raytherapy and apparatus of the prior art by providing an endoscopic x-raydevice that generates x-rays at the site of treatment and minimizesexposure of other tissues to irradiation.

SUMMARY OF THE INVENTION

A miniaturized x-ray apparatus for delivering x-rays to a selected sitewithin a body cavity includes a catheter having at least one lumen andan x-ray transparent window at a distal end thereof; an x-ray source inthe lumen adjacent said x-ray transparent window; a movable x-ray shieldpositioned to direct x-rays from the source through the x-raytransparent window to the selected site. The x-ray device ranges from 2mm to about 15 mm.

The x-ray source is positioned inside an x-ray shielded catheter lumen,i.e., the catheter lumen is impenetrable by x-rays except in the area ofthe x-ray transparent window which is described in more detail below.

The x-ray source includes a cathode and an anode and an insulatingmaterial. The anode and cathode are separated by a vacuum gap.Insulating material may surround the base anode and cathode.

Preferably, a separate lumen of the catheter includes a camera throughwhich medical personnel may observe the body lumen and procedure.

In a preferred embodiment, inflatable (anchoring or positioning)balloons are provided on the exterior of the endoscope to maintain thedesired position of the instrument once inserted into the lumen. Theseballoons may be filled with a gas via catheter lumens connected to a gasor fluid source. Preferably, the balloons are filled with a fluid thatabsorbs x-rays so that the fluid will help prevent irradiation ofundesired tissue. The gas and or fluid will also preferably help toabsorb heat generated during the procedure to prevent burning of localtissue. A thermocouple may be positioned on the exterior of theendoscope to monitor the temperature at the treatment site.

In an alternative embodiment, the catheter includes an x-ray source andthe anchoring balloons which are inflatable with gas or fluid asdescribed above. This embodiment does not include a shield.

Another alternative embodiment provides a catheter having a miniaturizedx-ray device and a stationary x-ray shield having an x-ray transparentwindow.

The invention is described in further detail hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a is a miniaturized x-ray device according to the prior art.

FIG. 2 is the x-ray emission pattern from the device in FIG. 1.

FIG. 3 is a longitudinal cross section of a miniaturized x-ray device ofthe present invention.

FIGS. 4a and 4 b are axial cross-sections of the device of FIG. 3showing the rotational motion of the x-ray shield about a central axis.

FIG. 5 is a cross-section of a catheter having circulation lumens toinflate positioning and/or anchoring balloons.

FIG. 6 is the catheter of FIG. 5 showing inflated positioning and/oranchoring balloons.

FIG. 7 is a miniature x-ray device having both positioning and anchoringballoons.

FIG. 8 is an embodiment of a miniature x-ray device having amulti-chambered balloon filled with coolant and having a thermocouple.

FIG. 9 is a preferred embodiment of a miniature x-ray device having alaser positioning system according to the invention.

FIG. 10 is a cross section of a miniature x-ray device having a laserpositioning system showing operation of the laser and x-ray shutters.

FIG. 11 is a preferred embodiment of a miniature x-ray catheter x-rayhaving an x-ray source located inside a catheter having an x-raytransparent window and a balloon positioning system.

DETAILED DESCRIPTION

FIG. 3 is a longitudinal cross section of a preferred x-ray apparatusaccording to the invention, inserted through the working channel of aendoscope (not shown) in a bodily lumen at a tumor site. The device 1includes an x-ray source 10 which is connected to power supply 12 byelectrically conductive cable 13, e.g. a coaxial cable. X-ray source 10includes a vacuum tube which maintains vacuum conditions therein andhouses the electrodes of the x-ray source. Power supply 12 deliverssufficient energy to x-ray source 10 to generate therapeuticallyeffective x-rays. Typically, voltages of from 10 to 60 kilovolts (kV)are needed to generate x-rays from x-ray source 10. X-ray source 10 islocated inside the lumen of x-ray tube 16 which is made of a materialsubstantially or completely impenetrable to x-rays like lead or steel,except where x-ray transparent window 18 is positioned so that x-raysmay exit the device and reach the desired site. Window 18 maycircumferentially extend about the entire circumference of the x-raytube 16, or may only be extend partially about the circumference of thex-ray tube.

Suitable materials for the window include beryllium, glass, ceramic,plastic, mica. Additional coatings of metal or insulating material maybe layered or coated on the window material as needed.

X-ray shield 15 is made of a material that is impenetrable to x-rayslocated in the catheter lumen and is rotatably connected to an externalcontroller such that it may be rotated about a central axis to blockx-rays from reaching non-selected tissue as shown in FIGS. 4a and 4 b.X-ray shield 15 may be connected to a rotatable knob located at theproximal end of apparatus 1 so that x-ray shield 15 may be manually orotherwise adjusted to the desired location, which is typically oppositethe site of treatment.

Device 1 preferably includes separate lumen for receiving a miniaturizedcamera, that may be retractably inserted into the body lumen. The camerais connected to a viewing screen so that the physician can view theposition of the device in the body lumen.

An important advantage of a device embodied above compared to apparatusof the prior art is easily discerned by comparing the device of FIG. 3with the prior art apparatus of FIG. 1. As shown in FIG. 2, the x-raypattern of the prior art device extends circumferentially from thelocation of the x-ray source in an unidirectional manner so thatselected and non-selected tissue is irradiated. The x-ray shield of thesubject apparatus limits allows medical personnel to limit radiationexposure to substantially only selected tissue, reducing exposure ofhealthy tissue to x-rays.

A preferred embodiment, shown in FIGS. 5,6 and 7 includes at least oneinflatable positioning balloon 20 adhered to the outer wall of the x-raytube. Positioning balloon 20 communicates with a gas or liquid reservoirvia a duct and is inflated after proper positioning of the apparatus inthe body lumen so that the position of the x-ray source is maintainedthroughout treatment. Positioning balloon 20 may be adhered to theexterior wall of the x-ray tube by a suitable adhesive. Alternatively,the balloons are positioned in compartments located inside a lumen ofthe device or in recesses provided in x-ray tube 16 so that they are notexposed until needed. It is preferred that a plurality of balloons areprovided. Alternatively, a multi-chambered balloon 21 is provided to aidproper positioning of the apparatus in the body lumen as shown in FIG.8.

In a particularly preferred embodiment, a gas or liquid coolant ispassed through balloon 20 via circulation lumens which communicate withthe interior of positioning balloon 20 and are connected to a gas orliquid reservoir. A respective circulation duct is provided for eachballoon or balloon chamber so that they may be independently inflated.The positioning balloons 20 may be inflated with a gas or a liquid, butan x-ray absorbent liquid is preferred. Normal saline is a particularlypreferred liquid because it has a high heat capacity, is x-rayabsorbent, and, in the unlikely event of leakage, is biocompatible withthe patient.

Optionally, anchoring balloons 22 may be positioned proximal and distalto positioning balloon 20 to steadfastly anchor the apparatus in thedesired site by fully inflating the anchor balloons, and finerpositioning adjustments may be made with positioning balloons 20 whichare placed nearly adjacent the x-ray source. In a particularly preferredembodiment, anchoring balloons 20 are positioned proximal and distal tothe x-ray window to anchor the endoscopic device at the desired site.

Thermocouple 26 may be optionally affixed or placed in the vicinity ofthe x-ray source to measure temperature during the procedure.Thermocouple 26 may be in the form of a bimetallic strip and isoperatively connected to a temperature display device so that thetemperature is monitored during the procedure.

Apparatus preferably includes a camera catheter 24 to view inside thebody cavity so that the endoscope can be properly positioned at thedesired site. The guide may be positioned in the same tube as the x-raysource or may be positioned in a tube parallel to the x-ray source 7.

In a particularly preferred embodiment shown in FIGS. 9 and 10 a lightsource 30 is provided in the x-ray catheter and is used to position thedevice such that substantially only the desired site is irradiated.Light source 30 is preferably a laser, but other types of illuminatingdevices may also be used. Light source 30 is positioned inside thecatheter lumen in the vicinity of x-ray source 10, but is a sufficientdistance from the source so that the light source is not damaged duringoperation. Alternatively, light source 30 may be separated from x-raysource 10 by a suitable insulating material. Light source 30 isoperatively connected to a power source.

Laser shutter 32 and x-ray shutter 33 are positioned one above the otherand are independently opened and closed via an operable connection withrespective manual opening devices. In a preferred embodiment, x-rayshutter 33 is automatically opened by an opening means when the x-ray isactivated so that it is only open during periods of operation of thex-ray source, and closes when the x-ray source is not activated. Theshutters operate in a known manner and are formed by a plurality ofretractable portions (32 a and 32 b; and 33 a and 33 b) which operate inconjunction with their respective counterpart to form an aperturethrough which light and x-ray may pass.

In operation, the selected site is illuminated as shown in FIG. 9 withlight source 33, and the field of illumination substantially correspondswith the field of irradiation. Thus, by simply illuminating the site ofoperation and viewing with the camera, it is possible to determine thesite of radiation prior to irradiation with the x-ray. Then the anchorand positioning balloons can be properly adjusted, and the site can beirradiated with the dose of x-ray.

FIG. 11 is an embodiment of a miniaturized x-ray device 100 having anx-ray source 101 attached to electrically conductive cable 102 which hasan inflatable balloons 20 adhered to an outer surface thereof Theballoons communicate with a fluid or gas source as described above toaid positioning of the x-ray source at the desired site.

The present invention also relates to methods of treatment, prophylaxisand adjunctive therapy using the miniaturized x-ray apparatus of thepresent invention. Suitable for use with other endoscopic equipment, thex-ray device is of an appropriate size such that it may be used to treatcancers of bodily lumens such as colorectal cancer, vaginal cancer,esophageal cancer, pulmonary cancers such as lung cancers, stomachcancer, oral cancers, or any cancer accessible by a bodily lumen bypositioning the device adjacent the target tissue and irradiating thetissue with a therapeutically effective amount of x-rays. In similarfashion, one can treat pre-cancerous conditions or conditions relatedwith cancer such as gastroesophageal reflux disease (GERD). Preferably,the selected site is illuminated prior to irradiation such that field ofirradiated tissue is determined prior to irradiation of the site.

The apparatus of the invention may be used in conjunction with imagingdevices such as visual, x-ray, magnetic or ultrasound to aid inpositioning of the device inside a body lumen.

Although the present invention has been shown and described with respectto several preferred embodiments thereof, additional embodiments will beapparent to the skilled artisan without departing from the spirit andscope of the invention.

All cited references are incorporated herein by reference.

What is claimed is:
 1. An apparatus for delivering x-rays to a selectedsite within a body cavity comprising: a catheter having at least onelumen and an x-ray transparent window at a distal end thereof; an x-raysource in said at least one lumen adjacent said x-ray transparentwindow; a movable x-ray shield positioned to direct x-rays from saidsource through said x-ray transparent window to said selected site; saidx-ray shield being operably connected to an external controller to movesaid x-ray shield when said catheter is inserted in a body cavity. 2.The apparatus of claim 1, further comprising inflatable anchoring orpositioning balloons affixed to the outer wall of the catheter andoperably connected to a gas or liquid reservoir by transport ducts. 3.The apparatus of claim 1, further comprising a thermocouple formeasuring temperature.
 4. The apparatus of claim 1, further comprising asecond catheter lumen for receiving a camera.
 5. The apparatus of claim1, further comprising a light source for illuminating the selected site.6. The apparatus of claim 1, further comprising a light source and anx-ray shutter for controlling the flow of x-rays and light through saidx-ray transparent window, said window also being transparent to light.7. The apparatus of claim 6, wherein said light source is a laser. 8.The apparatus of claim 1, wherein said external controller is arotatable knob located at a proximal end of the apparatus.
 9. A methodfor treating cancer accessible via a body lumen comprising: positioningan x-ray source of an apparatus adjacent the selected cancerous site,said apparatus comprising: a catheter having at least one lumen and anx-ray transparent window at a distal end thereof; an x-ray source insaid at least one lumen adjacent said x-ray transparent window; and amovable x-ray shield positioned to direct x-rays from said sourcethrough said x-ray transparent window to said selected site; moving saidx-ray shield to expose the selected cancerous site to said x-ray source;and irradiating the site with a therapeutically effective dose ofradiation.
 10. The method of claim 9, wherein the cancer is selectedfrom the group consisting of colorectal cancer, vaginal cancer,pulmonary cancer, esophageal cancer, oral cancer, and stomach cancer.11. A method for administering a therapeutically effective dose ofx-rays to a selected site comprising: positioning an x-ray source of anapparatus adjacent to the selected site, said apparatus comprising: acatheter having at least one lumen and an x-ray transparent window at adistal end thereof; an x-ray source in said at least one lumen adjacentsaid x-ray transparent window; a movable x-ray shield positioned todirect x-rays from said source through said x-ray transparent window tosaid selected site; a light source; and an x-ray shutter for controllingthe flow of x-rays and light through said x-ray transparent window, saidx-ray transparent window also being transparent to light; illuminatingthe body lumen with the light source to determine the field of tissueirradiation, the field corresponding to the illuminated tissue; movingthe x-ray shield to expose the selected site to the x-ray source; andirradiating the tissue in the radiation field with a therapeuticallyeffective dose of x-rays generated from the x-ray source.
 12. Anapparatus for delivering x-rays to a selected site within a body cavitycomprising: a catheter having an outer surface, at least one lumen andan x-ray transparent window at a distal end thereof; an x-ray source insaid at least one lumen adjacent said x-ray transparent window; arotatable x-ray shield positioned in said catheter lumen to directx-rays from said source through said x-ray transparent window to saidselected site; a light source; and inflatable anchoring or positioningballoons affixed to said outer surface of said catheter and operablyconnected to a gas or liquid reservoir by transport ducts.
 13. A methodfor treating precancerous conditions in a body cavity comprisingpositioning an x-ray source of an apparatus adjacent a selectedprecancerous site and irradiating the site with a therapeuticallyeffective dose of radiation, wherein said apparatus comprises a catheterhaving an outer surface, at least one lumen and an x-ray transparentwindow at a distal end thereof, an x-ray source in said at least onelumen adjacent said x-ray transparent window; a rotatable x-ray shieldpositioned in said catheter lumen to direct x-rays from said sourcethrough said x-ray transparent window to said selected site; a lightsource; and inflatable anchoring or positioning balloons affixed to saidouter surface and operably connected to a gas or liquid reservoir bytransport ducts.
 14. An apparatus for delivering x-rays to a selectedsite within a body cavity comprising: a catheter having at least onelumen and an x-ray transparent window at a distal end thereof; an x-raysource in said at least one lumen adjacent said x-ray transparentwindow; a rotatable x-ray shield positioned to direct x-rays from saidsource through said x-ray transparent window to said selected site. 15.A method of treating cancer in the lumen of a patient, comprisinginserting the apparatus of claim 14 into a lumen of a patient havingcancerous tissue therein; positioning the x-ray source proximate to thecancerous tissue, and applying sufficient power to said x-ray source togenerate x-rays and irradiate the cancerous tissue to treat the cancer.16. A method for treating precancerous conditions in a body cavitycomprising positioning an x-ray source of an apparatus adjacent aprecancerous site and irradiating the site with a therapeuticallyeffective dose of radiation, wherein said apparatus comprises a catheterhaving at least one lumen and an x-ray transparent window at a distalend thereof, an x-ray source in said at least one lumen adjacent saidx-ray transparent window; and a rotatable x-ray shield positioned todirect x-rays from said source through said x-ray transparent window tothe precancerous site.
 17. An apparatus for delivering x-rays to aselected site within a body cavity comprising: a catheter having atleast one lumen and an x-ray transparent window at a distal end thereof;an x-ray source in said at least one lumen adjacent said x-raytransparent window; a stationary x-ray shield positioned inside of saidcatheter lumen adjacent to said x-ray source to direct x-rays from saidx-ray source through said x-ray transparent window to said selectedsite.
 18. A method of treating a cancerous or precancerous condition inthe lumen of a patient, comprising inserting the apparatus of claim 17into a lumen of a patient having cancerous or precancerous tissuetherein; positioning the x-ray source proximate to the cancerous orprecancerous tissue, and applying sufficient power to said x-ray sourceto generate x-rays and irradiate the cancerous or precancerous tissue totreat the condition.
 19. The method of claim 18, wherein canceroustissue is treated.